NASA’s new exoplanet-hunting telescope set to launch on Monday.

NASA’s next exoplanet-hunting telescope is preparing for launch. The Transiting Exoplanet Survey Satellite (TESS), is scheduled to blast off aboard a Falcon 9 rocket on 16 April

TESS is take up the mantle of the Kepler Space Telescope, which is expected to run out of fuel by the end of this year. Kepler has found more than 5000 exoplanet candidates so far, and confirmed about half of them. TESS will be able to search 350 times more area of the sky than Kepler can, and is expected to find about 20,000 exoplanets in its first two years alone.

It will take about two months after launch to manouevre the satellite into its orbit – about half as far from Earth as the moon – and test its cameras. “After that, there’ll just be a flood of information,” says the mission’s principal investigator, George Ricker at the Massachusetts Institute of Technology.

Eyes on the sky

TESS will use the same transit method Kepler used to find planets. This involves watching a star for dips in its light as a planet passes between the star and the telescope. How often the dips repeat indicates how fast the planet circles its host star, and the amount of light that’s blocked tells us the size of the distant world.

Rather than looking at distant stars in a small area of sky, like Kepler did, TESS will look at closer stars over 85 per cent of the sky. It is optimised to observe smaller, cooler stars that emit mostly red light.

“90 per cent of the stars in the Milky Way emit in those red wavelengths, and then seem to have more planets than stars like the sun, especially smaller Earth-sized planets,” says Ricker. “Nature’s really saying, ‘look here, look here’ and that’s exactly what we’re going to do.”

Because those stars are so nearby and rich with planets, they will be ideal targets for the James Webb Space Telescope (JWST), due to launch in 2020. JWST will examine exoplanet atmospheres for signatures of life, which is only possible when their stars are relatively close.